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Wednesday, March 18, 2015

New Technology May Double Radio Frequency Data Capacity

As reported by Columbia Engineering: A team of Columbia Engineering researchers has invented a
technology—full-duplex radio integrated circuits (ICs)—that can be
implemented in nanoscale CMOS to enable simultaneous transmission and
reception at the same frequency in a wireless radio. Up to now, this has
been thought to be impossible: transmitters and receivers either work
at different times or at the same time but at different frequencies. The
Columbia team, led by Electrical Engineering Associate Professor Harish Krishnaswamy,
is the first to demonstrate an IC that can accomplish this. The
researchers presented their work at the International Solid-State
Circuits Conference (ISSCC) in San Francisco on February 25.“This is a game-changer,” says Krishnaswamy, director of the Columbia
high-Speed and Mm-wave IC (CoSMIC) Lab. “By leveraging our new
technology, networks can effectively double the frequency spectrum
resources available for devices like smartphones and tablets.”
In the era of Big Data, the current frequency spectrum crisis is one of
the biggest challenges researchers are grappling with and it is clear
that today's wireless networks will not be able to support tomorrow's
data deluge. Today's standards, such as 4G/LTE, already support 40
different frequency bands, and there is no space left at radio
frequencies for future expansion. At the same time, the grand challenge
of the next-generation 5G network is to increase the data capacity by
1,000 times.
So the ability to have a transmitter and receiver re-use the same
frequency has the potential to immediately double the data capacity of
today's networks. Krishnaswamy notes that other research groups and
startup companies have demonstrated the theoretical feasibility of simultaneous transmission and reception at the same frequency, but no
one has yet been able to build tiny nanoscale ICs with this capability.

“Our work is the first to demonstrate an IC that can receive and
transmit simultaneously,” he says. “Doing this in an IC is critical if
we are to have widespread impact and bring this functionality to
handheld devices such as cellular handsets, mobile devices such as
tablets for WiFi, and in cellular and WiFi base stations to support full
duplex communications.”
The biggest challenge the team faced with full duplex was canceling the
transmitter's echo. Imagine that you are trying to listen to someone
whisper from far away while at the same time someone else is yelling
while standing next to you. If you can cancel the echo of the person
yelling, you can hear the other person whispering.
“If everyone could do this, everyone could talk and listen at the same
time, and conversations would take half the amount of time and resources
as they take right now,” explains Jin Zhou, Krishnaswamy’s PhD student
and the paper’s lead author. “Transmitter echo or ‘self-interference’
cancellation has been a fundamental challenge, especially when performed
in a tiny nanoscale IC, and we have found a way to solve that
challenge.”
Krishnaswamy and Zhou plan next to test a number of full-duplex nodes
to understand what the gains are at the network level. “We are working
closely with Electrical Engineering Associate Professor Gil Zussman and
his PhD student Jelena Marasevic, who are network theory experts here
at Columbia Engineering,” Krishnaswamy adds. “It will be very exciting
if we are indeed able to deliver the promised performance gains.”

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I have more than 25 years of experience in development, design, and mobile communications products and technology. I also enjoy skiing, hiking, scuba, tennis, reading, traveling, foreign languages, and painting. I'm an active member of the National Ski Patrol (NSP) and volunteer my time at either Loveland Ski resort, or Ski Cooper.